Process for producing 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl

Abstract

A process for producing 2,2′-bis (trifluoromethyl)-4,4′-diaminobiphenyl which is useful as a raw material for polyimide resin, etc. In benzidine rearrangement of 3,3′-bis(trifluoromethyl) hydrazobenzene in the presence of an inorganic acid such as sulfuric acid aqueous solution or concentrated hydrochloric acid, use of a water-immiscible organic solvent such as toluene as reaction solvent can increase the yield of the product. 3,3′-bis(trifluoromethyl) hydrazobenzene can be synthesized by reduction of m-nitrobenzotrifluoride.

1. A process for producing 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl, which comprises that 3,3′-bis(trifluoromethyl)hydrazobenzene is rearranged by dropping a solution of 3,3′-bis(trifluoromethyl)hydrazobenzene dissolved in a water-immiscible organic solvent into an inorganic acid wherein the water-immiscible organic solvent is an aromatic hydrocarbon. 
     
     
       2. The process for producing 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl according to  claim 1 , wherein the inorganic acid is diluted sulfuric acid having a concentration of 10 to 80% by weight or concentrated hydrochloric acid. 
     
     
       3. The process for producing 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl according to  claim 2 , wherein the inorganic acid is used in an amount of 1 to 20 moles per 1 mole of 3,3′-bis(trifluoromethyl)hydrazobenzene. 
     
     
       4. The process for producing 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl according to  claim 1 , wherein the inorganic acid is used in an amount of 1 to 20 moles per 1 mole of 3,3′-bis(trifluoromethyl)hydrazobenzene.